Solubility of Calcium Carbonate Precipitated in Aqueous Solutions of Magnesium and Sulfate Salts1

H. E. Doner and

P. F. Pratt2

Abstract

Abstract

Calcium carbonates were precipitated in the presence of various salts at controlled CO2 partial pressures. Solubilities of the precipitates were compared with that of calcite and the precipitates were subjected to X-ray diffraction for the detection of crystalline products and in some cases analyzed for coprecipitated Mg. In NaCl solutions, the solubility of the carbonate was that of calcite. In MgCl2 solutions, the solubility of the precipitate was higher than that of calcite, both calcite and aragonite were detected and Mg was coprecipitated in the solid phase. In solutions of Na2SO4, the solubility of the precipitate was higher than in the case of the MgCl2 solutions and both calcite and vaterite were detected. In solutions of MgSO4, the solubility of the precipitate was intermediate between that of the MgCl2 solutions and the Na2SO4 solutions. The solubility product of CaCO3 seemed to be related mainly to the nature of the solid phase.

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